21121141551649 has 2 divisors, whose sum is σ = 21121141551650. Its totient is φ = 21121141551648.

The previous prime is 21121141551647. The next prime is 21121141551659. The reversal of 21121141551649 is 94615514112112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18062228001024 + 3058913550625 = 4249968^2 + 1748975^2 .

It is a cyclic number.

It is not a de Polignac number, because 21121141551649 - 2¹ = 21121141551647 is a prime.

It is a super-2 number, since 2×21121141551649² (a number of 27 digits) contains 22 as substring.

Together with 21121141551647, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21121141551647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560570775824 + 10560570775825.

It is an arithmetic number, because the mean of its divisors is an integer number (10560570775825).

Almost surely, 2^{21121141551649} is an apocalyptic number.

It is an amenable number.

21121141551649 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121141551649 is an equidigital number, since it uses as much as digits as its factorization.

21121141551649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 86400, while the sum is 43.

The spelling of 21121141551649 in words is "twenty-one trillion, one hundred twenty-one billion, one hundred forty-one million, five hundred fifty-one thousand, six hundred forty-nine".